The global clock is used in multiple areas to ensure that each component in the system has exactly the same time reference. For example, in the field of nuclear detection and flight time applications, multiple terminal systems often require a fully consistent time reference to meet the need of accurate time measurements. The method for obtaining and correcting the communication delay by way of timestamp communication between plurality of terminals is widely used in the field of communication, but this synchronization method is limited to the use of the existing communication protocol to achieve a global clock synchronization with a low accuracy, such as ms or sub-ms level. The accuracy of this method ultimately depends on the speed of the clock, that is, toggle frequency, and would not achieve a synchronization accuracy shorter than clock cycle. Therefore, the traditional method can only be, as shown in FIG. 1, setting in the system a unique clock source, and then connecting all the terminals needing for clock to the clock source, building a star network, and accurately ensuring that all connections (from the clock source to each terminal) have exactly the same length, thus ensuring that each terminal can obtain exactly the same synchronous clock signal. In this way, this requires special consideration of clock routing in complex systems consisting of very large-scale terminals, and a large amount of cable brings difficulties in system assembly, calibration, maintenance, and expansion. For example, if a new terminal is required, then it is necessary to add a fan-out at the clock source by a traditional method, which will necessarily change the hardware that has already been determined. Furthermore, in particular field, such as a scanning imaging system, as a plurality of (several to several thousands) detectors (i.e., terminals) all require a uniform time reference to satisfy a globally harmonized clock, and each detector requires a time measuring device at picosecond (ps) level, which makes the entire instrument system require a higher time resolution and the accuracy of the synchronization for time be required at the ps level, therefore, the equal length of the cable is required at the micron (um) level, which is too strict for the existing global clock to meet.